Switching assembly



G. A. REEsE SWITCHING ASSEMBLY April 12, 1960 Filed April 30, 1957 4 Sheets-Sheet l April 12, 1960 G. A. REESE swI'rcHING ASSEMBLY 4 Sheets-Sheet 2 Filed April 30, 1957 April 12, 1960 G. A. REESE 2,932699 swl'rcHING ASSEMBLY Filed Aprl'SO, 1957 4 Sheets-Sheet 3 WIM April l2, 1960 G. A. REEsE 2,932,699

swn'cHING ASSEMBLY Filed April 30, 1957 4 Sheets-Sheet 4 :36 35 Tn# N m p f@ fa N 25 United States Patent O SWITCHING ASSEMBLY Glenn A. Reese, Canoga Park, Calif., assgnor to The Magnavox Company, Los Angeles, Calif., a corporation of Delaware Application April 30, 1957, Serial N0. 656,054

25 Claims. (Cl. 20o-19) The present invention relates to electric switches and more particularly to an improved construction for a magnetically operated multiple switching assembly.

Many present day electronic circuits and apparatus require that a common channel be successively connected to each of a plurality of individual channels during each of a number or repeated operating cycles. These connections have Ibeen made in the past by mechanical commutators or by the use of specially constructed and controlled vacuum tubes.

The prior art switching arrangements for the most part, however, have proved either unduly expensive or incapable of the precise timing adjustment required in most apparatus in which this type of switching is required. Moreover, most of the prior art switching arrangements have been found to have a tendency to generate parasitic or noise signals as they are operated. v

Copending application Serial No. 652,968, filed April 15, 1957, by me discloses and claims a switching assembly in which most of the disadvantages inherent in the prior arrangements have been overcome and by which many of the prior art problems have been solved. This application describes a multiple rotary switch in which a plurality of individual switching units are disposed in an annular air gap. A magnetic flux is produced in this air gap and particular shifts or variations are introduced into the ilux at accurately positioned locations. Relative motion is created between the flux and the individual switching units so that the shifts or variations -in the ux sweep past the units and actuate magnetic aramatures in respective ones of the units. By providing a relatively large number of switching units and a relatively large number of spaced variations in the actuating iiux, a large number of switching operations can be produced in each operating cycle of the assembly.

As also described in the copending application, the individual switching units can be filled with a damping uid to reduce armature vibration to a minimum. Then, each switch is operated in a positive manner by the shifts `or variations in the tiux to provide a clean electrical switching action. This switching is .not accompanied to any appreciable extent by noise or other interference signals.

The present invention provides a magnetically controlled multiple switching assembly of the same general type as the one described in the copending application referred to above. The structure of the present invention, however, incorporates certain improved mechanical features which facilitate the fabrication of the assembly. For example, the assembly of the present invention provides liux in an annular air gap by an improved and ingenious arrangement of concentric magnetic rings and associated axially magnetized annular permanent magnets. Also, the switch-actuating shifts or variations of the flux in the air gap of this improved assembly are provided in one particular embodiment by integral tongues and cooperating channels formed in the magnetic rings.

A problem that has arisen in switching assemblies of the type described in the copending application has been the tendency of the armatures of the switching units to` develop extraneous pulses as the units paessed through the switch actuating variations in the magnetic flux These pulses proved to be troublesome from an interference standpoint in some applications in which the asseml bly has been used.

The structure and apparatus of the present invention successfully solves the problem referred to in the preceding paragraph, and it does this by the provision of a compensating shift or variation in the magnetic flux in correspondence with each of the switch-actuating shifts of variations. This compensating shift or variation does not have any nullifying eiect on the switch actuation by the primary shifts or variations, but the latter do function -to compensate and tend to reduce the noise signals developed by the primary shifts or variations on the armatures themselves.

The assembly of the present invention also incorporates other features which tend to reduce the production of noise pulses. The structure may be such that the two magnetic rings referred to above exhibit like poles to the annular air. gap. This provides a ux distribution in the air gap of balanced characteristics, and such a ux has little tendency to generate or induce noise signals in the armatures of the individual switching units.

As noted above, the precisely located switch-actuating shifts or variations in the magnetic flux in the annular air gap may conveniently be produced by tongues and mating channels on and in the magnetic rings defining the annular gap. in further accordance with the invention, these tongues and channeis may be shaped into particular congurations to reduce to a minimum the amplitude of any residual noise signals induced in the switch armatures.

In the drawings: t

Figure l is a perspective view of one embodiment of the rotor of the switching assembly of the invention with Ithe cover removed, this view showing a central turntable and an electrical motor for rotating the turntable and also showing a pair of magnetic rings supported on the turntable to define an annular air gap;

Figure 2 is an exploded view of the rotor showing the turntable of the switching assembly and concentric magnetic rings supported on the turntable, this view particularly illustrating compensating rings that are used in conjunction with the switch actuating rings to reduce to a minimum noise induced in the switching units;

t Figure 3 is a sectional view of the rotor of the switching assembly and is taken substantially on the line 3-3 of Figure l and particularly shows the arrangement of the magnetic rings dening the annular switch-actuating air gap and of the magnetic rings defining the compensating annular air gap and also illustrates the configuration and support of a pair of axially magnetized annular magnets which produce magnetic tiuxes in the air gaps;

Figure `4 is a top plan viewV of the rotor of Figure l, and this view reveals particularly the shape and configuration of a series of tongues and cooperating channels in the magnetic rings, `these tongues and channels being shaped in a particular manner to reduce the noise induced in the armatures of the individual switching units to a minimum;

Figure 5 is a top plan view of the cover of the assembly which is secured to a stationary frame surrounding the rotor, the illustrated cover being intended to support a plurality of individual, units so that each of the units extends into the annular air gap dened by the magnetic rings on the rotor;

Figure 6 is a sectional view of the cover and is taken substantially on the line 6-6 of Figure 5 and particularly illustrates the manner in which metallic inserts for the individual switching units are rigidly held on the cover;

terial such as, for example, cold rolled steel.

Figure 7 is a perspective view of one of the individual units, which unit may be suitably supported on the cover of Figure to extend through the cover down into the annular'air gap of the rotor of the switchingassembly; Figure 8 is a sectional view substantially on the line 8-8 of VFigure 7 and showing the internal components Vof the switching unit,`these components including a pair of fixed contacts and a resiliently mounted armature;

Figures Saand 8b are views taken respectively along the lines Srl-8a and Slt-8b of Figure 8 and showing further details of the switching unit armature.

Figures 9 and l0 are fragmentary schematic showings of one of the individual `switching units disposed in the annular air gap of the rotor of -the switching assembly, and illustrating the actuation of the armature of that switching unit as the unit is swept by a distortion in the `magnetic flux in the air gap;

Figure 1l is a fragmentary sectional diagrammatic view of the rotor and one of the switching units to illustrate the uniform and balanced distribution of the flux in the air gaps of the rotor for aiding in reducing to a minimum the noise induced on the switch armature; and

Figures 12 and 13 are fragmentary schematic showings of a second construction of the rotor and also illustrate the magnetic ield produced by the rotor at dierent positions of the rotor to act on the armature of a switch ing unit disposed in the annular air gap in the rotor.

The rotor portion of the switching assembly as shown in Figures 1 to 4, inclusive, is driven by an electric drivemotor 10. The motor 10 may be supported on any suit- `able horizontal supporting surface so that its drive-shaft 12 extends vertically upward. The motorv 10 preferably has a non-magnetic casing composed for example of aluminum, and it may conveniently be a llO volt synchronous motor of 17g() of a horsepower.

An outer stationary annular casing y14y is secured to the housing of the motor, and this casing has a shoulder 16 formed in it and extending around its top peripheral edge. 'Ihe shoulder 16 serves to receive and accurately position a cover for the assembly which shall be subsequently described.

The drive shaft 12 of the motor 10 is secured to a horizontal turntable 18 by means of a series of set-screws 20. These setscrews extend radially into a central hub 22 of the turntable through which the shaft 12 extends.

The turntable 18 includes an outer rim 24 which ex- -tends up from the plane of the turntable, and the turneach other.

A rst pair of magnetic annular rings 28 and 30 are supported in the annular channel 27 between the rims 26 and 24.

This rst pair of rings is composed of magnetic ma- These rings 28 and 30 `are of equal diameter and they are supported in the annular channel 27 in concentric relation with the turntable and against the inner rim 26. The rings 28 and 30 are supported on the turntable by appropriate set screws extending through holes 32 in the rings and through corresponding holes 34 in the turntable.

A Erst axially magnetized annular permanent magnet 36 is interposed between the magnetic rings 28 and 30 as shown, for example, in Figure 3. The annular permanent magnet 36 is held in place by the screws extending through the holesY 32 and 34 and through axially aligned holes (not shown) in the permanent magnet.

A second pair of magnetic annular rings 38 and 40 are also supported one over the other on the turntable 18. These latter rings have an inner diameter which is i assunse ff greater than the outer diameter of the rings 28 and 30. i

adjacent the outer rim 24. The rings 38 and 40 are securely held on the turntable by appropriate screws extending through holes 42 in the rings and through corresponding holes 44 in the turntable.

An annular axially magnetized permanent magnet 46 is interposed between the rings 38 and 40, as also shown in Figure 3. The annular magnet 46 is securely .held in place by the screws extending through the holes 42 and 44 and through corresponding holes in the magnet.

As shown, for example, in Figure 3, the rings 28 and 38 cooperate'to form a first annular air gap extending around the turntable in concentric relation with its axis of rotation. Likewise, the rings 30 and 40 define an annular air gap which is axially aligned with the rst annular air gap defined by the annular members 28 and 38. The annular permanent magnets 36 and 46 produce a magnetic flux in each of the annular air gaps. As shown Vin Figure 3, these magnets are disposed so that the annular rings 28 and 38 present north poles to the iirst annular airY gap, and the magnetic rings 30 and 40 present south poles to the second annular air gap. This produces -a flux distribution in the annular air gaps of the form shown in Figure ll and, as will be described, this particular configuration of the linx has been found to reduce residual noise induced in the armatures of the individual ,switching units. However, satisfactory switching operation can also be achieved by reversing the polarity of one of the annular magnets, so that the rings 28 and 38 and the rings 30 andv 40 presentunlike poles to their respective air gaps. l

The annular magnets 36 and 46, therefore, produce a magnetic flux in the upper annular air gap which shall be termed the switch-actuating air gap, and these magnets also produce magnetic flux in the lower air gap which shall be termed the compensating air gap.

Each of the magnetic rings 28 and 30 has a plurality -of radial channels formed at spaced angular positions in .their peripheral edges. These channels are ldesignated as 50 in Figures l, 2 and 4. Likewise, each of the magnetic rings 38 and 40 has a series of integral radial tongues 52 formed at selected angular positions corresponding to the positions of the channels 50. Each of the tongues l52 extends into the corresponding air gap radially inwardly and faces a corresponding channel Si).

The provision of the tongues 52 and the channels 50 in the magnetic rings provides precisely located shifts or variations in the magnetic flux in the switch-actuating vannular air gap and in the compensating air gap. These shifts or variations function, in a manner to be described,

Vfigure, the trailing edge of each of the tongues 52 and of each of the channels 50 is inclined at an angle of substantially 45. It has been found that when a switching unit is swept by a flux variation pro'duced by a shift in the leading edge of a tongue 52 and the associated chan nel 50, a noise pulse occurs. VHowever, this noise pulse usually occurs before the corresponding switch is actuated and does not usually interfere with the electrical apparatus controlled by the switch. However, a second noise pulse has been found to occur as the switch is swept by the trailing edges of each tongue and its associated channel. This second pulse is capable of causing interference in the controlled electric apparatus. By tapering and inclining the trailing edges of the tongues and channels in the manner shown in Figure 4, such noise pulses have been materially lengthened and Vtheir amplitudes substantially reduced so that their effect is lessened to a large extent. This configuration of the tongues 52 and 0f .the .channels 50 cooperates with the other features of aseaee '5 the switch to eliminate for all practical purposes the noise that would otherwise be induced in the switching units.

The stationary cover for the assembly is shown in Figures and 6. This cover is designated generally as 60, and it has an annular outer rim portion 62. This rim portion extends down from the o'uter periphery of the cover 60 to engage the shoulder 14 on the stationary portion 16 of the rotor assembly of Figure 1. Appropriate mounting holes 64 extend through the rirn po'rtion 62 and into corresponding threaded holes in the portion 16 so that the cover may be securely mounted von the assembly.

An annular channel 66 (Figures) is formed in the cover 60 in alignment with the annular air gaps of the Iotorassembly, which gaps are defined by the rings 28, 38 and 30, 40. This annular channel 66 is filled with any appropriate known potting compound. A mica-filled potting compound such as Epocast F made by Furane Plastics, Inc., of Los Angeles may be used. A plurality of individual inserts 68 formed, for example, of brass or other non-magnetic material are embedded in the potting compound and rigidly held angularly spaced from one another in position over the annular air gaps. These inserts 68 are drilled out to constitute appropriate mountings for respective ones of the stationary switches. This enables each switch to be held securely in a stationary position extending into the annular air gaps. The number of inserts 68 to be drilled out is dictated by the nurnber of individual switches to' be included in the assembly.

The inserts 68 are held in place by a pair of O-rings 70 and 72 which are disposed in annular grooves in the top and bottom surface of the cover 60. The O-rings themselves are held in place by a pair of annular clamps 74 and 76 which are disposed in respective channels in the top and bottom surfaces of the cover. These clamps are held by a series of studs 78 in clamping relationship with the resilient O-rings 70 and 72, which may be made from neoprene. This arrangement serves to support the individual switching units and their inserts rigidly in the stationary cover and to reduce vibration of the units to a minimum.

A switching unit appropriate for support in one of the drilled-out inserts 68 is shown in Figures 7 and 8. This unit may be equipped with appropriate ears on its outer surface to orient it properly in its insert and the gauge its depth. As sho'wn in Figure 7, for example, the switching unit has a lower tubular casing 80 composed of a non-magnetic electrically conductive material, such as brass. The casing 80 has a portion 80a which is attened and which is adapted to extend into both the switchactuating air gap and the compensating air gap of the rotor.

An armature is resiliently supported in the liattened portion 80a of the casing. This armature presents problems in that it must fulfill several distinct criteria. First, it must be resiliently mounted in the switching unit casing so that it can be conveniently actuated from one fixed contact to another, as will be described. Also, it must be capable of being attracted by a magnetic field so that it can be actuated in the manner described above. Moreover, it must be electrically conductive and capable of making and breaking electrical co'ntact with the fixed contacts without undue deterioration due to slight arcing conditions that may arise. Furthermore, it must be capable of actuation despite the presence of a compensating magnetic field, whose purpose will be described. Finally, it must be easy to' construct and simple to install in the switching unit casing.

All these requirements are met by the armature illustrated in Figures 8, 8a and 8b. To fulfill these needs, the armature, for example, may be formed of `an elongated rod `32 composed of ahard gold alloy. This insures against deterioration from contact arcing. The rod 82 lhas a attened portion 82a which provides the required degree of resiliency to the armature in a desired radial Hdirection. This ilattened configuration assures that .the

armature will be actuated only from one fixed contact to another and that it will not have any tendency to move in any other direction. A hole 8211 is provided in the flattened portion 82a to minimize the force exerted by the dampingiiuid against the pivotal movement of the rod 82 and to minimize turbulence of the fluid during such movement of the rod.

A sleeve 84 is fitted over the lower portion of the rod 82, and this sleeve may be composed of non-magnetic material such as brass. The sleeve 84 is in press-fit relationship with the internal surface of the flattened portion a of the lower tubular casing 80. The sleeve provides a rm mounting for the armature in the casing, and it enables the armature to be easily assembled in the casing.

An intermediate portion of the rod 82 is surrounded by a sleeve 86 composed of magnetic material such as soft iron. This latter sleeve renders the armature susceptible to magnetic action. A portion of the rod 82 protrudes from the upper end of the magnetic sleeve 86 to form the contact'portion of the armature. The magnetic sleeve 86 exhibits a clearance with the internal surface of the attened portion 80a of the casing 80 so' that the armature is free to move back and forth in a radial direction to a limited extent.

For example, the bore of the flattened portion of 80a of the casing may be the order of .067 inch, and the outer diameter of the armature sleeve 86 may be of the order of .O59 inch. The length of the attened portion 89a of the switching unit may be of the order of .187 inch, and this provides that the lower portion of the switching unit extends down into an annular well 88 (Figures 2, 3 and ll) formed in the turntable 18.

The upper portion of the switching unit includes a tubular casing 9) which may be composed of an electrically conductive, non-magnetic material (such as brass). The tubular casing 90 extends into press-fit with the lower casing 80. The casing 90 is filled with a potting compound 92 such as a hard insulating epoxy resin. This potting compound supports a pair of rod-like fixed electrical contacts 94 and 96 in spaced relation. The inner ends of the contacts 94 and 96 extend beyond the end of the casing 90 and into the casing 80 on either side of the contact portion of the armature rod 82. The arrangement is such that the armature is free to move from one of the fixed contacts 94 and 96 to the other so as to make and break electrical contact with the respective iixed contacts.

A lirst connecting lead 98 is soldered to the fixed contact 94, and a second connecting lead 100 is soldered to the fixed Contact 96. These connecting leads extend through the potting compound in the casing 90 and out through the switching unit. A third lead 102 is soldered to the inner surface of the casing 90. The lead 102 makes a connection with the armature rod 82 through the electrically conductive casings 90 and 80, and through the electrically conductive sleeve 84.

The inner ends of the fixed contacts 94 and 96 and the Contact portion of the armature rod 82, are formed in suitable dies to have the appropriate mating surfaces. A satisfactory alloy for the fixed contacts 94 and 96 is composed of 61.5% gold, 11.5% platinum, 1.5% lead, 24% silver, and 1.5% copper. The gaps between the contact portion of the armature rod and the fixed contacts 94 and 96 are each of the order of .001 inch.

The switching assembly is preferably lilled with a damping iiuid. A hydraulic oil produced by the Shell Oil Company and marketed by that company under the designation Aero Shell No. 12 is suitable for these purposes. Of course, many known types of damping iluids may be used. The fluid acts as a damping medium for controlling bounce between the armature rod 82 and the fixed contacts 94 and 96 and also acts to reduce erosion of the contact surfaces.

As shown in Figures 9 and l0, the switching assembly rotor is constructed so that, when one of the described switching units is disposed in `the switch-actuating air gap betweenthe magnetic rings 28 and 38, its armature 82 is moved'by the tlux in the gap into contact with the 'fixed contact 96. However, when the switching unit moves into one of the distorted areas of theux in the switch-actuating air gap between a tongue 52 and an .associated channel 50, the armature 82 is moved from its position shown in Figure 9 to its position shown in Figure 10 in which it contacts the fixed contact 94.

r As best shown in Figure 11, the provision of the switch-actuating air gap and of the compensating air gap and the mounting of the annular magnets 36 and 46 for the presentation of like poles by the magnetic rings 28, 38 and 30, 40 causes the flux in the gaps to assume the illustrated balanced configuration. The ux in the upper air gap is instrumental in providing the switchlactuating motion because it is further removed from the lever point of the switch armature. Since the flux in the upper air gap is further removed from the fulcrum of the armature 82 than the flux in the lower air gap, the upper lux produces a greater torque on the armature than the lower fiux. This causes the pivotal movement of the armature to be controlled by the ilux in the upper air gap.V However, any tendency for the flux in the upper gap to induce a noise voltage in the armature is minimized by the reverse tendency of the lower air gap. Therefore, the switching units are relatively free from induced noise voltages in their armatures.

The switching assembly of the invention, therefore, is capable of a multitude of successive switching operations which are periodically repeated in successive and rapid switching cycles. Moreover, each actuation of each switching unit is carried out in a positive and vibration damped manner. Also, the provision of the particular flux configurations and other means reduces the noise developed in the individual switching units to an absolute minimum.

As may be seen in Figure 4, a plurality of channel S and tongues 52 may be provided in the magnetic rings 38 and 40. As the magnetic rings 38 and 40 rotate, each of the associated channels 5t) and tongues 52 acts upon a switching unit to move the rod 82 in the switching unit from the contact 94 to the contact 96. In this way, the frequency of establishing electrical continuity through the contact 96 can be varied by varying the number of channels t) and tongues 52. This frequency can be varied without varying the speed of rotation of the rings 38 and 40. This is especially desirable when high speeds of testing are desired.

It has been found that approximately l0() microseconds are required for the armature 82 to spring free from the contact 94. Approximately 5() microseconds are required for the armature 82 to travel from the contact 94 to the contact 96. The contact make and break between the armature 82 and the contacts 94 and 96 produces a jitter of no more than a few microseconds. In this way, switch operation occurs in a time interval less than 200 microseconds. Since contact make and break can occur in such a short time interval, a relatively large number of channels 50 and tongues S2 can be provided in the rings 38 and 40 to control the operation of each switch unit. Furthermore, a relatively large number of switching units can be disposed around the annular periphery of the rings 38 and 40. For

example, as many as several hundred switching units can.

be provided in association with one pair of magnetic rings 38 and 40 and approximately half of that number of channels 50 and tongues 52 can be provided in one pair of rings 38 and 40.

The armature 82 is held against the contacts 94 and 96 by a force in the order of 50 to 100 Gs. Because of this considerable force, a relatively low resistance in the order of 0.5 ohm is produced between the armature andthe contact engaged by the armature. Furthermore,

" the switch constituting this invention is able to be used 8 inainstalla'tions where it might be subjected to large forces affecting the operation of lthe switch. For example, the switch can be used in airplanes which may be subjected to forces approaching 10 Gs in the airplane under certain maneuvers such as tight rolls. Even under these circumstances, the operation of the switch would not be affected since the force exerted on the switch by the maneuvers of the airplane would be considerably less than the force exerted on the armature 82 to hold it against one of the contacts 94 and 96. Furthermore, the switch constituting this invention can be disposed in any plane including a 'vertical plane because the gravitational force of 1 G would not affect the result.

By providing the rings 3,8 and 40 and by disposing the rings in an annular configuration, certain advantages are obtained in addition to those described above. These advantages result from the fact that flux traverses the air primarily in the gap between the rings 38 and 40. This minimizes the production of any leakage flux in the area external to the rings 38 and 40. `Since electrical leads may be disposed in the area external to the rings 38 and 40, minimizing the production of leakage iiux in such area may be important in preventing extraneous signals from being induced in the leads.

Figures 112 and 13 are views similar to Figures 9 and l0 and illustrate an alternate construction for the channels and tongues corresponding to the channels 50 and the tongues 52 in Figures 9 and l0. These channels and tongues are respectively illustrated at 110 and 112 in Figures l2 and 13. As may be seen, the channels 110 are provided with `throat portions of restricted length at positions near the tongues 112. The lengths of the channels then increase with progressive radial movements toward the centers of the rings. The tongues 112 are provided with configurations corresponding to the channels 110.

As may be seen, the flux threading the armature 82 changes rapidly in Figures l2 and 13 as the channels and the tongues 112 move past the armatures. This results from the particular configurations of the tongues and armatures. For example, the flux has to travel only a short path in Figure 12 through the air gap between the channel 110 and the tongue 112. In Figure 13 the flux has to travel a relatively long distance through the air to traverse the gap between the channel 110 and tongue 112. Since the travel path of the flux through the air gap changes relatively quickly, the armature 82 travels relatively quickly between the contacts 94 and 96. This causes signals of relatively large amplitude to be produced in comparison with the signals produced between the channels 5t) and the tongues 52 in Figures 9 and 10.

The durations of the signals induced by the channels and tongues having the configurations shown in Figures 12 and 13 are also considerably reduced below the durations of the signals produced by the channels and tongues shown in Figures 9 and 10. Signals of relatively short duration are desirable in certain applications of the switch constituting this invention. For example, by producing signals of short durat-ion at the leading and trailing edges of the channels 110 and the tongues 112, an increased time of stability is produced between the leading and trailing edges. Such increased times of stability may be `desired when this time is used to prepare a gate for the passage of` a signal from a `source external to the apparatus constituting this invention. Furthermore, by coupling 9 to be actuated from one operating condition to another, means for producing relative motion between said `field and said switching means to bring said switching means periodically under the inuence of said variations in said field, and means including magnetic means magnetically coupled to the armature for producing compensating variations in said field to counteract any tendency for said switching means to develop unwanted extraneous signals in response to such Variations in such field.

2. A magnetically controlled switching assembly including: means defining an air gap and for producing in said air gap a magnetic iiux exhibiting displacements in at least one position in said air gap, switching means disposed in said air gap and including an armature responsive to such displacements in the magnetic flux to control the operating condition of said switching means, means for producing relative motion between said walls and said switching means to bring said armature periodically under the iniiuence of said displacements in said magnetic ilux, and means including magnetic means magnetically coupled to the armature for producing compensating displacements in flux to counteract any tendency for said armature to develop unwanted extraneous signals in re- Isponse to such displacements in said magnetic iiux.

3,. A magnetically controlled switching assembly including: rotatable means `defining an annular air gap, means associated with said rotatable means for producing in said annular air gap a magnetic flux exhibiting variations in at least one position in said air gap, at least one stationary switching unit disposed -in said annular air gap and including an armature constructed at least in part of magnetic material and responsive to such variations in the magnetic flux to control the operating condition of said switching unit, means for rotating said rotatable means to produce relative motion between said magnetic iiux and said switching unit to brinor said armature periodically under the iniiuence of said variations in said magnetic ilux, and means operative upon the armature for producing compensating variations in magnetic ilux to counteract any tendency of said armature to develop unwanted extraneous signals in response to they variations in the magnetic flux.

4. A magnetically controlled switching assembly including: means for defining an air gap having displacements in at least one position and for producing in said air gap a magnetic iiux providing variations in at least the position of displacement of said air gap, at least one switching unit disposed in said air gap, said switching unit including a tubular housing and an elongated armature constructed of resilient electrically conductive nonmagnetic material, said switching unit further including means for mounting said armature in said housing and including a sleeve of magnetic material enveloping at least a portion of said armature, and means for producing relative motion between said means defining the air gap and said switching unit in a direction transverse to the ldirection of displacement of said air gap to bring said armature periodically under the influence of' said variations in said magnetic ux.

5. A magnetically controlled switching assembly including: a pair of annular members of magnetic material supported in concentric relation to define anI annular air gap between the members for the production of a magnetic ux, means associated with said annular members for producing flux in an axial direction across said air gap, one of said annular members having at least one radially extending tongue formed integrally therewith and extending into said air gap and the other of said' annular members having at least one radially extending channel formed in a peripheral edge thereof and in essentially facing relation with said tongue to produce flux variations at an angular position corresponding to said tongue andsaid channel, at least one switching unit disposed` in said annular air gap and including an armature responsive to such variations in the magnetic flux in' said annu- 10 lar air gap to control the operating condition of said switching unit, and means for producing relative motion between said switching unit and said pair of annular members to' bring said armature periodically under the influence of said variations in said magnetic flux.

6. A magnetically controlled switching assembly including: a pair of annular members of magnetic material, rotatable means for supporting said annular members in concentric relation to define an annular air gap between the members for the production of a magnetic flux, means associated with said annular members for producing ux in an axial direction across said air gap, means for rotating said rotatable means, said annular members being constructed to provide at least one radial variation in the air gap and to provide the radial variation in the air gap with a selected inclination at the trailing edge for the production of ilux variations at an angular position corresponding to said radial variation in the air gap and for the minimization of such linx variations at the trailing edge, and at least one stationary switching unit disposed in said annular air gap and including an armature responsive to such variations in the magnetic flux in said annular air gap to control the operating condition of said switching unit.

7. A magnetically controlled switching assembly including: a pair of annular members each composed of magnetic material and the inner diameter of one of said annular members exceeding the outer diameter of the other of said annular members, one of said annular members having a plurality of radial channels formed in a peripheral edge thereof at selected angular positions and the other of said members having a corresponding plurality of integral tongues in essentially facing relation with corresponding ones of said channels, rotatable means for supporting said annular members in concentric relation to define an annular air gap therebetween, annular permanent magnet means associated with said pair of annular members for producing in said annular air gap a magnetic ux having radial variations at positions corresponding to the respective positions of associated ones of said tongues and said channels, at least one switching unit disposed in said annular air gap and including an armature responsive to such variations in the magnetic iiux in said annular air gap to control the operating condition of said switching unit, and means for producing relative motion between said switching unit and' said pair of annular members to bring said armature periodically under the iniiuence of said variations in said magnetic ux.

8. A magnetically controlled switching assembly including: a pair of annular members each composed of magnetic material with the inner diameter of one of said annular members exceeding the outer diameter of the other of said annular members, non-magnetic rotatable means for supporting said annular members in concentric relation to deiine an annular air gap therebetween, a iirst annular axially magnetized permanent magnet supported on said rotatable means in concentric relation with said annular members, a second annular axially magnetized permanent magnet supported on said rotatable means in concentric relation with said annular members, one of said annular members having a plurality of radial channels formed in a peripheral edge thereof at selected angular positions and the other of said annular members having a corresponding plurality of integral radial tongues in essentially facing relation with corresponding ones of said channels to cooperate with said first and second magnets in producing in said annular air gap a magnetic flux having radial variations' at angular positions corresponding to associated ones of said tongues and channels in said annular members, at least one stationary switching unit disposed in said annular air gap and including an armature responsive to such variations in the magnetic flux in said annular air gap to control the operating condition-.of said switchingpunigand. means for rotating said assegnata 9. The combination'deiined in claim 8 in which said iirst and second annular permanent magnets are vaxially magnetized in a direction to cause said annular members to present like magnetic poles to said annular air gap.

10. A magnetically controlled switching vassembly including: a first pair of annular members of like diameter and each composed of magnetic material, a first axially magnetized annular permanent magnet interposed between the annular members of said rst pair, a second pair of annular members of like diameter and each composed of magnetic material, the inner diameter of the annular members of said second pair exceeding the outer diameter of said annular members of said irst pair, a second axially magnetized annular permanent magnet interposed between the annular members of said second pair, a non-magnetic turntable supporting said pairs of annular members and said interposed rst and second annular permanent magnets in concentric relation to .deiine iirst and second axially spaced annular air gaps,

the annular members of one of said pairs having a plurality of pairs of radial channels formed in a peripheral edge thereof at selected angular positions with the individual ones of the channels in each of said pairs being axially aligned, and the other pair of said annular members having a corresponding plurality of pairs of radial tongues in essentially facing Vrelation with correspond- -ing pairs of said channels, said iirst and second annular permanent magnets being axially magnetized in the same direction to produce in said air gaps magnetic flux lhaving radial variations Vat positions corresponding to associated ones of said tongues and channels in the annular members, at least one stationary switching unit disposed .in said first and second annular air gaps and including an armature responsive to such variations in the magnetic 'flux'in one of said annular air gaps to control the operating condition ofsaid switching unit, and means for imparting rotational motion to said turntable to bring said armature periodically under the influence of said Ivariations in said magnetic flux.

1l. A magnetically controlled switching assembly including: a tirst pair of annular members of like diameter and each composed of magnetic material, a rst axially magnetized annular permanent magnet interposed between the annular members of said first pair, a second pair of annular members of like diameter and each composed of magnetic material, the inner diameter ofthe annular members of said second pair exceeding the outer Vdiameter of said annular members of said first pair, a

second axially magnetized annular permanent'magnet interposed between the annular members of said second pair, means for supporting said pairs of annular members and said interposed annular permanent magnets in concentric relation to define first and second axially spaced annular air gaps, means for producing in said air .gaps magnetic flux having radial variations at selected angular positions therein, at least one switching unit disposed in said annular air gaps and including an armature responsive to such variations in the magnetic flux in one of said annular air gaps to control the operating condition of said switching unit, and means for imparting relative motion between said rotatable means and said switching unit to bring said armature periodically under the influence of said variations in said magnetic flux.

l2. An assembly for controlling at least a iirst particular switching unit, including: magnetic means constructed to define an air gap for receiving the iirst particular switching unit and to produce a magnetic flux in said air gap having variations in at least one position in said air gap, and means co-operative with the magnetic means for producing compensating variations in magnetic flux to counteract any tendency of the iirst particular switching unit to develop extraneous signals.

13. A magnetic rotor assembly for controlling at least 12 a first par-ticular switching unit, including: rotatable means defining an annular airY gap for receiving Vthe first 'particular' switching unit, first magnetic means associated with said rotatable means for producing in said annular air gap a 'magnetic flux having radial variations in at least one position in said air gap, means for rotating said rotatable means to produce relative motion between said magnetic ux and the first particular switching unit,

`members exceeding the outer diameter of the other of said annular members, rotatable means for supporting said annular members in concentric relation to define an annular air gap therebetween for receiving the first particular switching unit, a first annular axially magnetized permanent magnet supported on said rotatable means in concentric relation with said annular members and interposed between one of said annular members and said rotatable means, a second annular axially magnetized permanent magnet supported on said rotatable means in concentric relation with said annular members and interposed between the other of said annular members and said rotatable means, one of said annular members havinga plurality of radial channels formed in a peripheral edge thereof at selected angular positions and the other of said annular members having a corresponding plurality of integral radial tongues in essentially facing relation with corresponding ones of said channels, and means for rotating said rotatable means to produce relative motion between the flux in said air gap and the stationary rst particular switching unit.

l5. The combination defined in claim 14 in which said first and second annular permanent magnets are axially magnetized in a direction to cause said annular members to present like magnetic poles to said annular air g Il. A switching assembly including: at least one switching unit lhaving an elongated armature pivoted at one end thereof, means constructed to deline an air gap for receiving the switching unit, means magnetically coupled to the armature for producing a magnetic flux in said air gap having variations in at least one position in said air gap at an advanced position along said armature wlth respect to the pivoted end thereof, and means magnetically coupled to the armature for producing compensating Ivariations in said magnetic flux at an intermediate position along said armature with respect to said pivoted end thereof to counteract any tendency of said switching unit to develop Vextraneous signals.

l7. A switching assembly including: at least one switching unit including a tubular casing and an elongated armature composed at least in part of magnetic material extending along the interior of said casing and pivoted at one end thereof, means constructed to define an air gap for receiving the switching unit, means for producing a magnetic flux in said air gap having variations in at least one position in said air gap at an advanced position along said armature with respect to the pivoted end thereof, and means for producing compensating Variations in said magnetic flux at an intermediate position along said armature with respect to the pivoted end thereof to counteract any tendency of said switching unit to develop extraneous signals.

18. A switching assembly as set forth in claim 16 in which the switching unit includes a tubular casing, an elongated electrically conductive rod extending along the Yinterior of said casing, a first sleeve extending over said rod at one end ofV the rod and in pressdit relationship 13 with said rod and with the internal surface of said casing to mount said rod for pivotal movement in said casing, and a second sleeve fitted over an intermediate portion of said rod, said second sleeve being composed of magnetic material.

19. A switching assembly as set forth in claim 17 in which the switching unit includes a tubular casing composed of non-magnetic material, an elongated conductive rod extending along the interior of said casing, a first sleeve extending over said rod at one end of the rod and in press-fit relationship with said rod and with the `internal surface of said casing to mount said rod for pivotal movement in said casing, a second sleeve tted over an intermediate portion of said rod spaced from said first sleeve and composed of magnetic material, and said rod having a flattened portion intermediate said first and second sleeves.

20. A switching assembly, including: means including first and second Walls spaced to define a continuous air gap between the walls and having contours to define a displacement in said air gap in at least one position along said walls and having properties to produce in said air gap a field exhibiting variations at the position of displacement, switching means disposed in said air gap and responsive to such variations in said field to be actuated from one operating condition to the other, means for producing relative motion between said walls and said switching means to bring said switching means periodically under the influence of the variations in the iield, and means for providing compensating elds at the position of displacement of said air gap to minimize any tendencies for said switching means to develop unwanted signals as a result of the variations in the field.

21. A switching assembly as set forth in claim 2O in which the compensating means include third and fourth walls spaced Ito define a second continuous air gap between the walls and having contours to define a displacement in said air gap at a position corresponding to the displacement in the air gap between the first and second walls and having properties to produce in said second air gap a eld opposing the field produced in the air gap between the first and second walls and in which the switching means is also disposed in said second air gap.

22. A switching assembly, including, means including rst and second walls spaced to define a continuous air gap between the walls and provided with a channel in the rst wall and a tongue in a contiguous position of the second wall to define a displacement in said air gap in the direction between the walls and having properties to produce in said air gap magnetic iiux at successive positions along said air gap in the direction between the walls and to product variations in such magnetic fiux at the position of the tongue and channel, switch means disposed in said air gap and including an armature responsive to such variations in the magnetic flux to control the operating condition of such switching means, and means for producing relative motion between said walls and said switching mean to bring said armature periodically under the inuence of said variations in said magnetic ux, the tongue and channel being shaped at their forward ends in the direction of relative motion to produce a change in the operating condition orf said armature in accordance with such variations in magnetic flux and being shaped at their trailing ends in the direction of relative motion t0 prevent any changes in the operating condition of said armature.

23. Apparatus as set forth in claim 19 in which the switching assembly is rfilled with a damping fluid and in which a hole is provided in the iiattened portion of the rod to facilitate movements of the rod in the damping fluid.

24. ln a switching unit, a casing made from a nonmagne-tic material, there being hydraulic fluid in the casing, a first sleeve made from a non-magnetic material and disposed in the casing at one end of the casing, an elongated rod supported in the sleeve at one end and extending thorugh the casing for pivotal movement relative to the casing, the rod being provided with a flattened portion at the end contiguous to the sleeve to limit pivotal movement of the rod in one direction, there being a hole in the attened portion to minimize turbulence upon a pivotal movement of the rod, a second sleeve made from a magnetic material and disposed on the rod at an intermediate position on the rod for pivotal movement with the rod in accordance with the magnetic field linking the magnetic material, a first electrical contact carried by the rod at the free end of the rod, and a second electrical contact i'ixedly supported by the casing for engagement with the first electrical contact upon a pivotal movement of the rod.

25. In a switching unit, a casing having a first portion made from an electrically insulating material and having a second portion made from an electrically conductive material, the casing being filled with a damping uid, a first sleeve made from a non-magnetic material and disposed within the first portion of the casing, a rod supported by the first sleeve and extending from the sleeve through the first portion of the casing and into the second portion of the casing, the rod having a flattened portion to minimize pivotal movement in the attened direction, there being a hole in the attened portion to minimize turbulence of the damping iiuid upon a pivotal movement of the rod, a second sleeve supported by the rod at an intermediate position in the rod and made from a magnetic material for a pivotal movement of the rod upon the occurrence of flux linking the magnetic material, a rst electrical contact disposed at the free end of the rod at a position within the second portion of the casing, and a second electrical contact fixedly disposed in electrically isolated relationship to the casing within the second portion of the casing for engagement with the first electrical contact upon a pivotal movement of the rod.

References Cited in the le of this patent UNITED STATES PATENTS DeLucia July 29, 1958 Attesting Oioer UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,932v699 April l2I 1960 Glenn A.lv Reese It is herenv certified that error appears in the-printed specification of the `above `numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 13, line 52, for Hproduct" read produce --5 line 53, for "switch" read switching --13 same column 13v line 58q y for "mean" read means --3 column l4 line 16v for .'thorugh" read through Signed and sealed this 8th day of November 1960Q (eEAL) Attest:

KARL H, AXLINE ROBERT C. WATSON Commissioner of Patents UNITED STATES PATENT oEEICE CERTIFICATE OF CORRECTlON Patent No, 9329699 April 12I 1960 Glenn A., Reese ears in the-printed specification It is herebjr certified that error app rection and that the said Letters oi the above `numbered patent requiring oor Patent should read as corrected below.

Column l3 line 529 for product read -m produce --g line 53 for "switch" read switching "1; same column 13s1 line 58, for "mean'l read means g column lllV line lu for "thorugh" read through Signed and sealed this 8th day of November 1960.n

i S EA L) Attest:

KARL H, AXLNE Attesting icer ROBERT C. WATSON Commissioner of Patents 

